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https://issues.apache.org/jira/browse/CASSANDRA-1546?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12919454#action_12919454
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Kelvin Kakugawa commented on CASSANDRA-1546:
--------------------------------------------
zhu,
np, let me clarify. The way both #1546 and #1072 work is that counter updates
are only aggregated in the MT. You can imagine that each SST on-disk
represents the aggregated updates for those keys when they were MTs (in the
past)--snapshots in time, if you will. So, on a counter read, the counts for a
given key are aggregated across all the relevant SSTs on disk. On a related
note, during compaction, counts across the compacted SSTs are aggregated into
the resultant SST. So, writes are cheap.
You may want to reference my presentation on distributed counters:
http://www.slideshare.net/kakugawa/distributed-counters-in-cassandra-cassandra-summit-2010
> (Yet another) approach to counting
> ----------------------------------
>
> Key: CASSANDRA-1546
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1546
> Project: Cassandra
> Issue Type: New Feature
> Components: Core
> Reporter: Sylvain Lebresne
> Assignee: Sylvain Lebresne
> Fix For: 0.7.0
>
> Attachments: 0001-Remove-IClock-from-internals.patch,
> 0001-v2-Remove-IClock-from-internals.patch,
> 0001-v3-Remove-IClock-from-internals.txt, 0002-Counters.patch,
> 0002-v2-Counters.patch, 0002-v3-Counters.txt,
> 0003-Generated-thrift-files-changes.patch, 0003-v2-Thrift-changes.patch,
> 0003-v3-Thrift-changes.txt, marker_idea.txt
>
>
> This could be described as a mix between CASSANDRA-1072 without clocks and
> CASSANDRA-1421.
> More details in the comment below.
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